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31.
Marwa F. Mansour Ehab F. El‐Kady Nabawia M. El‐Guindi Samir M. El‐Moghazy Ann Van Schepdael 《Journal of separation science》2013,36(20):3432-3439
A simple CE method was developed and validated for the simultaneous determination of chlordiazepoxide (CHL), amitriptyline, and nortriptyline (mixture I) or the determination of CHL and imipramine (mixture II) using the same BGE. Sertraline and amitriptyline were used as internal standards for the first and second mixtures, respectively. The method allows amitriptyline to be completely separated from its impurity and main metabolite nortriptyline, which can be quantified from 0.2 μg/mL. The separation was achieved using 20 mM potassium phosphate buffer pH 5 containing 12 mM β‐cyclodextrin and 1 mM carboxymethyl‐β‐cyclodextrin. UV detection was performed at 200 nm and a voltage of 15 kV was applied on an uncoated fused‐silica capillary at 25°C. These experimental conditions allowed separation of the compounds to be obtained in 7 min. Calibration graphs proved the linearity up to 40 μg/mL for CHL, up to 100 μg/mL for amitriptyline and imipramine, and up to 5 μg/mL for nortriptyline. The accuracy and precision of the method have been determined by analyzing synthetic mixtures and pharmaceutical formulations. The analytical results were quite good in all cases indicating that the method was linear, sensitive, precise, accurate, and selective for both mixtures. 相似文献
32.
Fotouh R. Mansour Christine L. Kirkpatrick Neil D. Danielson 《Chromatographia》2013,76(11-12):603-609
An ion-exclusion chromatography (IELC) comparison between a conventional ion-exchange column and an ultra high-performance liquid chromatography (UHPLC) dynamically surfactant modified C18 column for the separation of an aliphatic carboxylic acid and two aromatic carboxylic acids is presented. Professional software is used to optimize the conventional IELC separation conditions for acetylsalicylic acid and the hydrolysis products: salicylic acid and acetic acid. Four different variables are simultaneously optimized including H2SO4 concentration, pH, flow rate, and sample injection volume. Thirty different runs are suggested by the software. The resolutions and the time of each run are calculated and feed back to the software to predict the optimum conditions. Derringer’s desirability functions are used to evaluate the test conditions and those with the highest desirability value are utilized to separate acetylsalicylic acid, salicylic acid, and acetic acid. These conditions include using a 0.35 mM H2SO4 (pH 3.93) eluent at a flow rate of 1 mL min?1 and an injection volume of 72 μL. To decrease the run time and improve the performance, a UHPLC C18 column is used after dynamic modification with sodium dodecyl sulfate. Using pure water as a mobile phase, a shorter analysis time and better resolution are achieved. In addition, the elution order is different from the IELC method which indicates the contribution of the reversed-phase mode to the separation mechanism. 相似文献
33.
Coordination polymer of unstable zinc borohydride and pyrazine is prepared and used as an stable, efficient and selective bench top reducing agent for a variety of organic compounds. 相似文献
34.
Highly sensitive FRET-based fluorescence immunoassay for aflatoxin B1 using cadmium telluride quantum dots 总被引:1,自引:0,他引:1
Roya Zekavati Shahabeddin Safi Seyed Jamal Hashemi Tavoos Rahmani-Cherati Meisam Tabatabaei Afshin Mohsenifar Mansour Bayat 《Mikrochimica acta》2013,180(13-14):1217-1223
We report on a competitive immunoassay for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET) from anti-aflatoxin B1 antibody (immobilized on the shell of CdTe quantum dots) to Rhodamine 123 (Rho 123-labeled aflatoxin B1 bound to albumin). The highly specific immunoreaction between the antibody against aflatoxin B1 on the QDs and the labeled-aflatoxin B1 brings the Rho 123 fluorophore (acting as the acceptor) and the QDs (acting as the donor) in close spatial proximity and causes FRET to occur upon photoexcitation of the QDs. In the absence of unlabeled aflatoxin B1, the antigen-antibody complex is stable, and strong emission resulting from the FRET from QDs to labeled aflatoxin B1 is observed. In the presence of aflatoxin B1, it will compete with the labeled aflatoxin B1-albumin complex for binding to the antibody-QDs conjugate so that FRET will be increasingly suppressed. The reduction in the fluorescence intensity of the acceptor correlates well with the concentration of aflatoxin B1. The feasibility of the method was established by the detection of aflatoxin B1 in spiked human serum. There is a linear relationship between the increased fluorescence intensity of Rho 123 with increasing concentration of aflatoxin B1 in spike human serum, over the range of 0.1–0.6 μmol·mL?1. The limit of detection is 2?×?10?11 M. This homogeneous competitive detection scheme is simple, rapid and efficient, and does not require excessive washing and separation steps. Figure
A nanobiosensor has been fabricated based on a competitive immunoassay for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET). In the presence of aflatoxin B1, it will compete with the labeled aflatoxin B1-albumin complex for binding to the antibody-QDs conjugate so that FRET will be increasingly suppressed. 相似文献
35.
H. H. Mahmud A. Mansour F. M. Ezz-Eldin 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):261-272
Radiation indicator as well as radiation shielding of extremely high dose have been proposed. Three different types of a-SiO2 namely, G1-xerogel, G2-fused and G3-natural silica were monitored by EPR before and after γ-irradiation. The E′-center has been used for EPR radiation characterization of a-SiO2 with assuming that the signal intensity changes with γ-irradiation differently as those of other EPR signals do. Formation and decay of the E′-center are closely related with its precursor, diamagnetic oxygen vacancies. Gamma ray of large dose (500 kGy) creates oxygen vacancies giving up-and-down irradiation effects, which, therefore, might be useful for high dose radiation indicator (G1) and radiation shielding (G2 and G3). 相似文献
36.
Mahmoud Emam Doaa R. Abdel-Haleem Maha M. Salem Lina Jamil M. Abdel-Hafez Rasha R. Abdel Latif Shaimaa Mahmoud Farag Mansour Sobeh Mohamed A. El Raey 《Molecules (Basel, Switzerland)》2021,26(6)
Infections associated with the emergence of multidrug resistance and mosquito-borne diseases have resulted in serious crises associated with high mortality and left behind a huge socioeconomic burden. The chemical investigation of Lavandula coronopifolia aerial parts extract using HPLC–MS/MS led to the tentative identification of 46 compounds belonging to phenolic acids, flavonoids and their glycosides, and biflavonoids. The extract displayed larvicidal activity against Culex pipiens larvae (LC50 = 29.08 µg/mL at 72 h). It significantly inhibited cytochrome P-450 monooxygenase (CYP450), acetylcholinesterase (AChE), and carboxylesterase (CarE) enzymes with the comparable pattern to the control group, which could explain the mode of larvae toxification. The extract also inhibited the biofilm formation of Pseudomonas aeruginosa by 17–38% at different Minimum Inhibitory Concentrations (MICs) (0.5–0.125 mg/mL) while the activity was doubled when combined with ciprofloxacin (ratio = 1:1 v:v). In conclusion, the wild plant, L. coronopifolia, can be considered a promising natural source against resistant bacteria and infectious carriers. 相似文献
37.
Mansour Mohammadpour Farhad Hosseinzadeh-Lotfi Gholam-Reza Jahanshahloo 《The Journal of the Operational Research Society》2015,66(7):1206-1211
Data envelopment analysis (DEA) is a non-parametric approach based on linear programming that has been widely applied for evaluating the relative efficiency of a set of homogeneous decision-making units (DMUs) with multiple inputs and outputs. The original DEA models use positive input and output variables that are measured on a ratio scale, but these models do not apply to the variables in which negative data can appear. However, with the widespread use of interval scale data and undesirable data, the emphasis has been directed towards the simultaneous consideration of the positive and negative data in DEA models. In this paper, using the slacks-based measure, we propose an extended model to evaluate the efficiency of DMUs, even if some variables are measured on an interval scale and some on a ratio scale. Moreover, the extended model allows for the presence of all interval-scale variables, which are capable of taking both negative and positive values. 相似文献
38.
39.
Giuseppa Di Bella Patrizia Licata Vito Pellizzeri Hedi Ben Mansour Giacomo Dugo 《Natural product research》2018,32(12):1402-1406
Two species of edible clams Venerupis aurea laeta and Cerastoderma edule glaucum from Ganzirri Lake (Sicily, Italy) were investigated to determine OCP and PCB residues by GC-MS. Thirty-five samples were examined for two years in order to perform: a) their actual contamination; b) the daily dietary exposure of seafood consumers to the pollutants in question. In all the clams analysed in this study, PCB and OCP (4,4′-DDE) residues are always below the limits fixed by law. It seems that there is some seasonality of concentrations observed. In fact the more high concentrations of residues are detected in the hot months, for both species and years. Given the consumption of clams and the values obtained in this study for the two species analysed, it is possible estimate that the average daily dietary intake of NDL-PCB and of 4,4′-DDE for adults is really low. 相似文献
40.
An analysis is presented to investigate the effects of chemical reaction, thermal radiation and heat generation or absorption on unsteady free convective heat and mass transfer along an infinite vertical porous plate in the presence of a transverse magnetic field and Hall current. The governing partial differential equations are formulated and transformed by using a similarity transformation into a system of ordinary differential equations. The resulting equations are solved numerically using a fourth‐order Runge–Kutta scheme along with the shooting method. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. Numerical results for the velocity, temperature and concentration distributions are shown graphically for different parametric values. The effects of parameters on the local friction coefficients, the Nusselt number and Sherwood numbers are depicted in tabulated form. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献